1. Field of the Invention
One embodiment of the present invention relates to an input device. One embodiment of the present invention relates to a display device. One embodiment of the present invention relates to an input/output device. One embodiment of the present invention relates to a touch panel.
Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention disclosed in this specification and the like include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device, an input/output device, a driving method thereof, and a manufacturing method thereof.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A semiconductor element such as a transistor, a semiconductor circuit, an arithmetic device, and a memory device are each an embodiment of a semiconductor device. An imaging device, a display device, a liquid crystal display device, a light-emitting device, an input device, an input/output device, an electro-optical device, a power generation device (including a thin film solar cell, an organic thin film solar cell, and the like), and an electronic device may each include a semiconductor device.
2. Description of the Related Art
In recent years, a display device provided with a touch sensor as a position-input device has been in practical use. For example, a display device provided with a touch sensor is called a touch panel, a touch screen, or the like. Examples of a portable information terminal provided with a touch panel are a smartphone and a tablet terminal.
As one of display devices, there is a liquid crystal display device provided with a liquid crystal element. For example, an active matrix liquid crystal display device, in which pixel electrodes are arranged in a matrix and transistors are used as switching elements connected to respective pixel electrodes, has attracted attention.
For example, an active matrix liquid crystal display device including transistors, in which metal oxide is used for a channel formation region, as switching elements connected to respective pixel electrodes is already known (Patent Documents 1 and 2).
It is known that a liquid crystal display device is classified into two major types: transmissive type and reflective type.
In a transmissive liquid crystal display device, a backlight such as a cold cathode fluorescent lamp or an LED is used, and a state in which light from the backlight is transmitted through liquid crystal and output to the outside of the liquid crystal display device or a state in which light is not output is selected using optical modulation action of liquid crystal, whereby bright and dark images are displayed. Furthermore, those displays are combined to display an image.
In a reflective liquid crystal display device, a state in which external light, that is, incident light is reflected at a pixel electrode and output to the outside of the device or a state in which incident light is not output to the outside of the device is selected using optical modulation action of liquid crystal, whereby bright and dark images are displayed. Furthermore, those displays are combined to display an image.
Examples of the display device include a light-emitting device including a light-emitting element such as an organic electroluminescent (EL) element or a light-emitting diode (LED), and an electronic paper performing display by an electrophoretic method or the like.
Patent Document 3 discloses a flexible light-emitting device in which an organic EL element is used.